1. Field of the Invention
The present invention relates to a saccharide-derived monomer, to a method for manufacturing the same and to a highly-dielectric polymer consisting of the said monomer. More particularly, it relates to a highly dielectric polymer especially having a high dielectric constant and an excellent resistance to hygroscopicity useful as a solid electrolyte in the use as a binder for electroluminescence (EL) element, a film condenser dielectric material, polymer batteries, an electrochromic element, an electrolytic condenser, an electric double layer condenser, lithium ion secondary batteries, etc. and also to a saccharide-derived monomer giving the said monomer as well as a method for manufacturing the same.
2. Description of the Related Art
Organic electronic materials such as a binder for EL elements of a dispersed type are requested to have characteristics such as high dielectric property, low hygroscopicity for making their life long, unchangeability of electric characteristic values upon temperature change (heat resistance), and high adhesion to fluorescent substances and electrode surfaces. Under such circumstances, examples of the organic polymer used for a binder for EL elements of a dispersed type are (1) cyanoethylated products of polymers having many hydroxyl groups such as polyvinyl alcohol, cellulose or derivatives thereof and pullulan, (2) homo- or copolymer of cyanoethylated acrylate monomers and (3) homo- or copolymer of vinylidene fluoride (fluorine rubber of a vinylidene fluoride type).
However, the above cyanoethylated products (1) have high hygroscopicity and the life of the EL element of an organic dispersion type (hereinafter, just referred to as xe2x80x9cEL elementxe2x80x9d) is short (reduction of luminance upon luminescence and of luminescent efficiency) whereby, in the manufacture of EL elements, an antihygroscopic countermeasure and a tightly closed sealing of the EL element itself by a non-permeable transparent material are necessary. However, even that is not satisfactory for the life extension whereupon they are entirely unable to be used for EL elements of the so-called packageless type having no tightly closed seal. In the case of the polymer of (2), hygroscopicity is improved as compared with the cyanoethylated products of (1) and, in the EL elements where a tightly closed seal is applied, an effect of improving the life is noted but, in the EL elements of a packageless type, that is still unsatisfactory for practical use. In the case of the fluorine rubber of a vinylidene fluoride type (3), it is less hygroscopic and is used especially for EL elements of a packageless type but there is a serious disadvantage that the dielectric constant is insufficient and a sufficient luminance is hardly available.
The present invention is to solve the above-mentioned problems in the prior art and an object of the present invention is to provide a highly dielectric polymer having both low hygroscopicity and high dielectric property and having electric characteristics required for organic electronic materials and also to provide a saccharide-derived monomer which gives the said polymer.
The present inventors have carried out an intensive study for polymers having a high dielectric constant and an excellent resistance to hygroscopicity and have found that a polymer having the characteristics of a high dielectric constant and a low hygroscopicity is obtained when a monomer where polymerizable functional group is introduced into hydroxyl group or other functional group contained in a saccharide or a saccharide-derived compound while cyanoethyl group is introduced into all of or a part of the remaining hydroxyl group or other functional group is prepared followed by polymerizing the said monomer whereupon the present invention has been accomplished.
Thus, the above-mentioned object of the present invention can be appropriately achieved by a saccharide-derived monomer in which polymerizable functional group is introduced into hydroxyl group or other functional group contained in a saccharide or a saccharide-derived compound while cyanoethyl group is introduced into all of or a part, of residual hydroxyl group or other functional group and also by a highly dielectric polymer prepared by polymerization of the said monomer.
The said saccharide-derived monomer can be manufactured by a method where cyanoethyl group is introduced into all of or a part of hydroxyl group or other functional group contained in a saccharide or a saccharide-derived compound having polymerizable functional group or by a method where a part of hydroxyl group or other functional group contained in a saccharide or a saccharide-derived compound is protected by a protecting group, then cyanoethyl group is introduced into all of or a part of the residual hydroxyl group or other functional group and, after that, deprotection is carried out and then polymerizable functional group is introduced into the said deprotected hydroxyl group or other functional group whereby the present invention can be achieved.
Further, the object of the present invention can be appropriately achieved by the above-mentioned saccharide-derived monomers in which the polymerizable functional group is an ethylenic unsaturated group and the saccharide or the saccharide-derived compound contains a structure of a cyclic pyranose type or a cyclic furanose type. Now, the present invention will be illustrated in detail as hereunder.
There is no particular limitation for the saccharide and the saccharide-derived compound of the present invention but natural or synthetic ones may be appropriately selected and used depending upon the required characteristics. Thus, examples of the monosaccharide are trioses such as glycerol aldehyde and dihydroxyacetone; tetroses such as erythrose, erythrofuranose, treose, treofuranose and erythrulose; pentoses such as aldopentose, ketopentose, aldepentopyranose, aldopentofuranose and ketopentofuranose; aldopentoses such as arabopyranose, arabofuranose, xylopyranose, xylofuranose, ribofuranose, ribopyranose, lyxopyranose and lyxofuranose; ketopentoses such as ribulose, ribulofuranose, xylulose and xylulofuranose; hexoses such as aldehexose, aldehexopyranose, alfohexofuranose, ketohexose, ketohexopyranose and ketohexofuranose; alkohexoses such as glucose, glucopyranose, glucofuranose, galactose, galactopyranose, mannose, mannopyranose, talose and talopyranose; hetohexoses such as fructose, fructofuranose, fructopyranose, sorbose, sorbopyranose, tagatose, tagatopyranose, psicose and psicopyranose; aldoheptoses such as glycero-galacto-heptose, glycero-galacto-heptopyranose, glycero-manno-heptose, glycero-manno-heptopyranose, glycero-gluco-heptose and glycero-gluco-heptopyranose; ketoheptoses or heptuloses such as altro-heptulose, altro-hetulopyranose, anhydro-altro-heptulopyranose, manno-heptulose, manno-heptulopyranose, talo-heptulose, talo-heptulopyranose, allo-heptulose, allo-heptulopyranose, altro-heptulose and altro-heptulopyranose; ketooctoses or octuloses such as glycero-manno-octulose, glycero-manno-octulopyranose, glycero-galacto-octulose and glycero-galacto-octulopryanose; ketononoses or nonuloses such as erythro-gluco-nonulose, erythro-gluco-nonulopyranose, erythro-galacto-nonulose and erythro-galacto-nonulopyranose; deoxy sugars; dideoxy sugars; amino sugars; sulfur sugars; branched sugars; acidic sugars; sugar alcohols; sugar esters; sugar ethers; and glycosides such as O-glycoside, N-glycoside and C-glycoside.
Examples of natural oligosaccharides and synthetic oligosaccharides are maltoligosaccharide, celloligosaccharide, isomaltoligosaccharide, gentioligosaccharide, nigeroligosaccharide, laminarioligosaccharide, glucan oligomer, sophoroligosaccharide, chitoligosaccharide, N-acetylchitoligosaccharide, lactoligosaccharide, mellioligosaccharide, inuloligosaccharide, fructan, xylan and mannan. Still more examples are the above-mentioned saccharide compounds and saccharide derivatives where those compounds are chemically modified.
The high dielectric property of the highly dielectric polymer of the present invention is believed to be expressed by a steric structure of a cyanoethyl group having a big dipolar moment and, especially when a saccharide having an asymmetric structure among the above-mentioned saccharides and saccharide derivative compounds is used, polarity of the dipolar moment is fixed giving a preferred result. Further, in the case of the substance having a cyclic structure of a pyranose type or a furanose type, steric structure is completely fixed and, in addition, polarity of dipolar moment is also fixed based upon the structure of the whole saccharide as a result of the plane structure depending upon the ring structure whereby the more preferred result is available.
Moreover, with regard to a polymerizable functional group which is to be introduced in the present invention, a functional group which is able to be subjected to condensation polymerization, addition polymerization and ring-opening polymerization can be used and there is no particular limitation therefor. Further, that which is not usually called as a functional group may be also used as other polymerizable functional group so far as it has a polymerizable chemical structure. Specific examples are condensation-polymerizable functional groups such as a carboxyl group, a hydroxyl group, an amino group, an acid halide group and a mercapto group; addition-polymerizable functional groups such as an ethylenic unsaturated group; and ring-opening-polymerizable functional groups such as a cyclic ether, a cyclic imine, a cyclic lactone, a cyclic lactam, a cyclic olefin, a cyclic sulfide, a cyclic polysiloxane and chlorophosphazene while examples of functional group which can be used for other polymerization methods are isocyanate, phenylene oxide, diphenylmethane, a phenyl group, chlorobenzy, a diazo group, a diene group, an acetylene group and a sulfur nitride group.
Among the above, the preferred one is a radical polymerizable functional group, i.e. an ethylenic unsaturated group, whereby the selective range is broad as a functional group-containing compound in introducing a polymerizable functional group into a saccharide or a saccharide derivative compound and a polymerization takes place under a relatively mild condition. Among the said ethylenic unsaturated group, that which is derived from acrylic acid or methacrylic acid is particularly preferred in industry in view of polymerization characteristics and handling.
There is also no limitation for the numbers of the polymerizable functional group which is to be introduced in a saccharide or a saccharide derivative compound (hereinafter, may sometimes be referred to as a saccharide compound) so far as it is 1 or more per molecule of the saccharide compound. When one functional group is introduced, the resulting highly dielectric polymer where a saccharide-derived monomer is polymerized is soluble in a solvent and, therefore, it is possible to make the said polymer into various shapes. When the numbers of the functional group introduced are 2 or more, cross-linking may be introduced into the polymer whereby, although the product is thermally and chemically stable, its processing ability is restricted. Therefore, it goes without saying that some measures such as that necessary shape-making is done at the same time with the polymerization are required.
There is no particular limitation for a method of introducing the polymerizable functional group but a method where a compound having a functional group which is necessary in the planned polymerization method can be bonded either directly or indirectly may be appropriately used. In case an ethylenic unsaturated group giving a good result is introduced, a monomer compound having a functional group which is polymerizable with a hydroxyl group contained in the saccharide or the saccharide derivative compound or with other functional group such as a hydroxyl group, a carboxyl group, an amino group or a glycidyl group and also having an ethylenic unsaturated group is used and is chemically bonded to a saccharide.
Specific examples of the compound for introducing a (meth)acrylic acid group among the ethylenic unsaturated group are (meth)acrylic acid chloride, hydroxyethyl(meth)acrylate, hydroxpropyl(meth)acrylate, hydroxybutyl(meth)acrylate, hydroxyphenoxypropyl(meth)acrylate, glycerol mono(meth)acrylate, chlorohydroxy(meth)acrylate, polypropylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, polytetramethylene glycol mono(meth)acrylate, (meth)acrylic acid per se and monofunctional(meth)acrylate such as dimethylaminoethyl, monohydroxyethyl succinate, monohydroxyethyl phthalate, tetrahydrofurfuryl, glycidyl and isocyanatoethyl. Incidentally, (meth)acrylate means both acrylate and methacrylate.
Next, there is also no particular limitation for a method of introducing a cyanoethyl group into a saccharide compound so far as it is able to achieve the object of the present invention. Specific examples are the so-called cyanoethylating reaction where acrylonitrile is subjected to a Michael addition to a hydroxyl group of a saccharide compound using an alkaline catalyst, a substitution reaction using 2-chloropropane nitrile and a substitution reaction where a hydroxyl group is a releasing group by means of tosylation and the like and, among them, a cyanoethylation where the reaction easily takes place is preferred. With regard to a method of the cyanoethylation, a method mentioned in a review by Bruson, H. A., et al. in Organic Reaction, 1949, volume 5, page 79 may be appropriately utilized.
With regard to the numbers of the cyanoethyl group to be introduced, there is no limitation at all so far as the introduction takes place into at least one of the hydroxyl groups or other functional groups other than the group into which polymerizable function group was already introduced. However, the more the amount of the cyanoethyl group per unit weight, the higher the dielectric constant and, therefore, the more the numbers of the cyanoethyl group, the better for achieving a high dielectric property which is an object of the present invention. The most preferred case is that cyanoethyl groups are introduced into all of the residual hydroxyl groups or other functional groups. Incidentally, when hydroxyl groups remain, that results in a cause of hygroscopicity whereby there is a tendency that such groups are to be as little as possible and that supports the fact that the more the cyanoethyl group, the better. It goes without saying that the use of a saccharide or a saccharide derivative compound having many hydroxyl groups or other functional groups is preferred.
With regard to the functional group into which the above-mentioned polymerizable functional group is introduced or a cyanoethyl group is introduced, there is no particular limitation so far as it is a functional group contained in the saccharide and any group which is derived from nature or is introduced by synthesis may be used. To be more specific, its examples are a hydroxyl group which fundamentally constitutes the saccharide and other functional groups such as a primary, secondary or tertiary amino group, a carboxyl group, a carbonyl group, amercaptogroup, analdehydegroup, asulfonicacidgroup, a phosphoric acid group and an ether group. With regard to such a functional group and its reaction method, examples are mentioned in xe2x80x9cTokagaku no Kiso (Fundamental Sugar Chemistry)xe2x80x9d by Kimiko Abu and Nobuko Seno, 1984, published by Kodansha and the method mentioned therein may be appropriately used.
With regard to a method for the manufacture of the saccharide-derived monomer in the present invention, the first method is that a cyanoethyl group is introduced into all of or a part of the hydroxyl groups or other functional groups contained in a saccharide or a saccharide-derived compound having the above-mentioned polymerizable functional group whereby the object of the present invention can be achieved. According to such a method, the reaction steps become short and that is advantageous. On the contrary however, it is necessary that the chemical structure is not chemically affected even by a strong alkali which is used in the cyanoethylating reaction. The second method is that a part of hydroxyl groups or other functional groups contained in the above-mentioned saccharide or saccharide derivative compound are protected by a protective group, then a cyanoethyl group is introduced into all of or a part of the remaining hydroxyl groups or other functional groups, a deprotection is carried out and a polymerizable functional group is introduced into the said deprotected hydroxyl groups or other functional groups whereupon the object of the present invention is achieved. Although the manufacturing steps become many in this method, there is an advantage that, when the protective group is selected upon necessity, a saccharide-derived monomer can be obtained surely and in a good yield without being affected by a chemical reaction by a cyanoethylation.
There is no particular limitation for the protective group which is used in the present invention but that which is commonly used in organic synthesis may be appropriately selected and used. Specific examples thereof are a trimethylsilyl ether group, a methoxyethoxymethyl ether group, amethyl ether group, amethyl ester group, abenzyl ether group, a benzyl ester group, a butoxycarbonyl group, dimethoxyltrityl ether group, acetyl group, methoxymethyl ether group and a tetrahydropyranyl ether group. Further, there is no particular limitation for a method of introducing them but a reaction corresponding to each of the protective group which is commonly used may be appropriately selected and used.
A method for polymerization of a saccharide-derived monomer for preparing a highly dielectric polymer which is a final product of the present invention may be freely selected depending upon the characteristics of the polymerizable functional group. Specific examples thereof are a condensation polymerization, an addition polymerization, a ring-opening polymerization, a polyaddition, an addition condensation, a hydrogen transfer polymerization, a polymerization by oxidation (or dehydrogenation), a polymerization by recombination, a polymerization by Diels-Alder reaction and a cyclization polymerization. Among them, a radical polymerization having little chemical influence on the saccharide-derived monomer is preferred. Incidentally, in this radical polymerization, any of a catalytic polymerization, an optical polymerization, a photosensitization polymerization, a radiation polymerization, etc may be used.
Further, in this polymerization, either a homopolymer of the saccharide-derived monomer of the present invention or a copolymer thereof with other monomer may be used and are, depending upon the required characteristics and use, any of them may be appropriately selected. In addition, there is no particular limitation for the comonomer for the copolymerization but a monomer depending upon the polymerization method may be appropriately used.
Examples of the copolymerizable monomer in the case of a saccharide-derived monomer having a polymerizable ethylenic unsaturated group suitable to the present invention are alkyl(meth)acrylates such as those having methyl, ethyl, propyl, butyl, amyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, stearyl, 2-ethylhexyl or cyclohexyl;
monofunctional(meth)acrylate such as that having 2-methoxyethyl, 3-methoxybutyl, 2-butoxyethyl, ethoxydiethylene glycol, methoxytriethylene glycol, methoxydipropylene glycol, phenoxyethyl, phenoxydiethylene glycol, nonylphenoxyethyl, isobornyl, dicyclopentenyloxyethyl and glycidyl;
polyfunctional(meth)acrylates such as 1,6-hexanediol di(meth)acrylate, 1,9-nonandiol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tridipropylene glycol di(meth)acrylate, polydipropylene glycol di(meth)acrylate and hydroxypivalate;
unsaturated nitriles such as (meth)acrylonitrile and vinylidene cyanide; vinyl halides and vinylidene halides such as vinyl chloride, vinyl bromide, vinyl fluoride and vinylidene chloride; unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid and itaconic acid and salts thereof; unsaturated ketones such as methyl vinyl ketone, phenyl vinyl ketone, methyl isobutenyl ketone andmethyl isopropenyl ketone; vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate and vinyl benzoate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; (meth)acrylamide and alkyl-substituted compounds thereof; unsaturated sulfonic acid such as vinylsulfonic acid, (meth)allylsulfonic acid and styrenesulfonic acid and salts thereof;
styrenes such as styrene, methylstyrene and chlorostyrene and alkyl- or halo-substituted compounds thereof; allyl alcohol or esters or ethers thereof; basic vinyl compounds such as vinylpyridine, vinylimidazole, dimethylaminoethyl(meth)acrylate and diethylaminoethyl(meth)acrylate; unsaturated aldehydes such as acrolein and methacrolein; cross-linking monomers such as glycidyl(meth)acryalte, N-methylol(meth)acrylamide, hydroxyethyl(meth)acryalte, triallyl isocyanurate, divinylbenzene and methylenebis(meth)acrylamide;
sulfonic acid-containing monomers such as vinylsulfonic acid, vinyltoluenesulfonic acid, sulfopropyl(meth)acryalte, sulfoethyl(meth)acryalte, styrenesulfonic acid, (meth)acrylamidomethanesulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid and (meth)allylsulfonic acid and salt-type monomers thereof; carboxyl group-containing monomers such as (meth)acrylic acid, itaconic acid, 2-(meth)acryloyloxyethylphthalic acid, 2-(meth)acryloyloxyethylsuccinic acid, 2-(meth)acryloyloxyethyl-2-hydroxyethylphthalic acid, 2-(meth)acryloyloxyethylhexahydrophthalic acid and 2-(meth)acryloyloxyethylmaleic acid and salty-type monomers thereof; and
phosphoric acid-containing monomers such as (meth)acryloyloxyethyl acid phosphate, bis(meth)acryloyoxyethyl acid phosphate, (meth)acryloyloxyethyl phenyl acid phosphate, (meth)acryloyloxyethyl diphenyl acid phosphate and (meth)acryloyloxy polyalkyl acid phosphate and salt-type monomers thereof. Incidentally, the above-mentioned term xe2x80x9c(meth)xe2x80x9d means both acrylate and methacrylate; both acrylamide and methacrylamide; and both allyl and methallyl.
There is no particular limitation for the molecular weight of the highly dielectric polymer of the present invention and, when the polymerizing condition is appropriately selected, the polymer having a molecular weight which corresponds to the aimed use is polymerized and is used. There are many cases where the highly dielectric polymer of the present invention is used after being filmed and, when the molecular weight is too low, strength of the film may be insufficient. On the contrary, when the molecular weight is too high, viscosity of the solution for making a film becomes very high whereby it may be difficult to prepare a thin and uniform film. When one kind of a highly dielectric polymer is used solely, the preferred range is within 10,000-500,000 in terms of a weight-average molecular weight. When it is used together with other polymer, strength can be born by other polymer and, therefore, that having a low molecular weight may be used and that of about 300 to 10,000 in terms of a weight-average molecular weight may be used as well.
There is no particular limitation for the form of the highly dielectric polymer of the present invention in use but any form depending upon the required use may be used. Usually, it is used in a form of being coated on a substrate or in a form of film although the present invention is not limited thereto. In actual use, the said polymer may be used solely or organic or inorganic additives for improving the dielectric property or other additives for giving other functions may be used together and they are not out of the coverage of the present invention. After it is polymerized and when the resulting polymer is insoluble in solvents due to formation of a cross-linking structure or the like, it is also possible that the monomer is applied and the polymer in an applied form as such is polymerized by ultraviolet ray, electronic ray or the like to give a highly dielectric polymer.
In the highly dielectric polymer of the present invention, many cyanoethyl groups having a high dipolar moment are introduced into hydroxyl group and/or other functional group of the saccharide located at the side chain and, therefore, a big dipolar moment is available. In addition, when the saccharide or the saccharide derivative compound has an asymmetric structure or when it has a cyclic structure such as a pyranose type or a furanose type, a dipolar moment having a polarity due to asymmetry of the saccharide or to cyclic structure of the saccharide is resulted whereby it is believed that, as a result, a high dielectric property is achieved. In addition, the main chain of the polymer of the present invention consists of strong bonds such as a carbon-carbon bond whereby a polymer of a high practical value having mechanical characteristics such as strength and ductility as well is resulted. Moreover, design of the structure as a monomer can be freely carried out and, accordingly, it is possible to give a polymer having a low hygroscopicity where hydrophilic groups such as a hydroxyl group of the monomer can be completely sequestered.